U.S. Pat. No. 4,191,001 discloses a method of exteriorly insulating existing concrete block walls by applying furring strips, expanded polystyrene boards over the furring strips, chicken wire stapled to the polystyrene boards, and a concerete coating over the chicken wire and polystyrene boards. The butt joints between boards are sealed with a polystyrene glue. The stapling of the chicken wire and the glueing of the butt joints is relatively time consuming. Further, the polystyrene board has a relatively high coefficient of thermal expansion. Therefore, the concrete coating must have an elastomeric bonding agent to compensate for thermal expansion and contraction of the board. In addition, polystyrene board is not acceptable under various fire codes.